Delaware Joins 24 States Suing EPA Over Climate Rule Reversal

Delaware has joined 23 other states in filing a federal lawsuit against the EPA for eliminating a key scientific finding used to regulate greenhouse gas emissions. The Trump administration's reversal removes the legal foundation for most climate regulations, including vehicle emissions standards.

WASHINGTON — Delaware has joined a coalition of 24 states filing a federal lawsuit against the Environmental Protection Agency, challenging the agency’s decision to eliminate a crucial scientific determination that served as the foundation for regulating greenhouse gas emissions nationwide.

The legal action, filed Thursday in the U.S. Court of Appeals for the District of Columbia Circuit, targets the EPA’s recent elimination of a 2009 scientific determination that classified carbon dioxide and other greenhouse gases as threats to public health and safety. This Obama-era determination provided the legal framework for virtually every climate regulation implemented under the Clean Air Act, affecting vehicles, power plants, and other sources of emissions contributing to global warming.

Eliminating this finding removes all emissions standards for automobiles and trucks and may lead to the dismantling of additional climate regulations affecting stationary facilities like power plants and oil and gas operations.

This marks the second significant legal challenge to the rule reversal, following an earlier lawsuit filed by environmental and public health organizations last month.

The coalition’s legal filing argues that the EPA’s decision to abandon the endangerment determination represents a failure of the agency’s fundamental duty to protect Americans.

“Rather than assisting Americans in confronting our current reality, the Trump administration has opted for denial, eliminating essential protections that form the cornerstone of federal climate change response,” stated New York Attorney General Letitia James, who spearheaded the lawsuit alongside top legal officials from Massachusetts, California, and Connecticut.

The legal challenge includes participation from 24 states, 10 municipalities, and five counties, all under Democratic leadership.

“Climate change represents a real threat that is already impacting our citizens and economic stability,” declared Massachusetts Attorney General Joy Campbell. “When federal authorities turn their backs on legal requirements and scientific evidence, ordinary citizens bear the burden.”

Campbell added that Massachusetts “has consistently pioneered efforts to shield our communities from greenhouse gas emission hazards and we take pride in stepping forward once more to champion this battle for our collective future.”

The U.S. Supreme Court established in a groundbreaking 2007 ruling that carbon dioxide and similar greenhouse gases qualify as “air pollutants” under Clean Air Act provisions. Following this high court decision in Massachusetts v. EPA, courts have consistently dismissed legal attempts to overturn the endangerment determination, including a 2023 ruling by the D.C. appeals court.

EPA representative Brigit Hirsch characterized the recent lawsuit as unrelated to “legal principles or substantive arguments.” She claimed the plaintiffs “are obviously driven by political motivations.”

Hirsch explained that the EPA “thoroughly examined and reassessed the legal basis” of the 2009 determination considering recent court rulings, including a 2022 Supreme Court decision that restricted how clean air legislation can be applied to reduce carbon dioxide emissions from power facilities.

Beyond New York, Massachusetts, California, and Connecticut, the legal action includes attorneys general from Arizona, Colorado, Delaware, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, New Jersey, New Mexico, Nevada, North Carolina, Oregon, Rhode Island, Vermont, Virginia, Washington, and Wisconsin, plus the District of Columbia and U.S. Virgin Islands.

Pennsylvania’s Department of Environmental Protection has also joined, along with municipalities including Albuquerque, Boston, Chicago, Cleveland, Columbus, Denver, Los Angeles, New York, and San Francisco, plus five counties across California, Colorado, Texas, and Washington state.

Legal experts expect this dispute will ultimately reach the Supreme Court again, which now maintains a significantly more conservative composition than during its 2007 decision.